The present invention relates to the field of photography and, more particularly, to an accessory mounting plate for coupling accessories to a compact self-developing camera.
Any given combination of camera and film has inherent limitations. The film is designed to faithfully reproduce colors, images, and lighting conditions projected thereon by the camers's optical system. The optics generally have a well defined limited range of performance in terms of field of view, depth of focus, and minimum focusing distance.
When photographic conditions are encountered which fall outside of these limits, it is both desirable and necessary to modify the performance of the camera and film combination by utilizing accessory filters, lenses, and other aids.
For example, the source illuminating the scene to be photographed may introduce artificial coloring. By using a compensating filter in front of the objective lens, the natural color of the scene may be restored in the photographic rendition. Other filters may be employed to compensate for harsh lighting on high contrast subjects, haze, fog, low contrast subjects, etc. In other instances, it may be desirable to produce a photograph in which the natural colors and lighting conditions are modified for aesthetic reasons by utilizing suitable filters and/or polarizers.
The field of view and/or depth of focus of the camera's optical system may be changed by using suitable supplementary lenses in front of the objective. These may include wide angle, magnifying, telephoto, and other types of lenses.
Other accessories, such as a lens shade, may be employed to prevent light originating from points outside of the camera's optimum field of view from entering the objective lens.
In the prior art, such accessories are usually mounted on the front end of the objective lens by means of a threaded coupling ring surrounding the lens.
The self-developing camera with which the accessory mounting system of the present invention is adapted to be used is extremely small and compact in relation to the size of the positive print produced. Examples of such cameras may be found in U.S. Pat. Nos. 3,641,889 and 3,678,831.
To provide a precision threaded coupling ring around the objective lens is expensive because of the small diameter of the lens and its mounting arrangement. Furthermore, the threaded coupling system is relatively slow in terms of the time it takes the user to change accessories.
More importantly, the lens is mounted in a small (approximately 11/2 inches .times. 3/4 inch .times. 4 inches) parallelepiped shaped housing section which also mounts a flash unit socket, a photocell, a light/dark exposure control wheel, a focusing wheel, a cable release socket, and a camera cycle start button. Therefore, the available space for attaching an accessory holder or mounting system to the lens housing is at an absolute minimum. Not only must the holder properly position the accessory in front of the objective, but its physical size and structural attachment must not block or impair the operation of any of the above-mentioned controls.
In a copending application, Ser. No. 246,917, filed on Apr. 24, 1972 by E. R. Brandt, now U.S. Pat. No. 3,747,490, an accessory holder is disclosed for use with the same compact self-developing camera. It comprises a resilient band of material which conforms to the shape of the lens housing and snaps therearound to hold the accessory in front of the objective lens. While this structure functions properly, it does have the drawback of being relatively expensive. Due to the flexing of the band encountered when mounting and removing the holder, it must necessarily be fabricated from an expensive material to preclude plastic deformation and/or stress fracture.